Metal composition.



ran snares manna entice.

HENRY K. SANDELL, OF CHICAGO, ILLINOIS, ASSIGNOR T HERBERT S. MILLS, OF

CHICAGO, ILLINOIS.

METAL comrosrrron.

No Drawing.

' My invention relates to improvements in y metal compositions. Moreparticularly the invention is concerned with a metallic alloy comprisingnickel and tungsten and containing a considerable percentage of carbon.

. I find that such a body has. peculiar properties which render itspecially desirable for use as a contact point for making and breakingelectrical circuits. In order to prepare my new metallic substance theapparatus and procedure fully described in my prior application No.-119,656, filed September 12, 1916, may conveniently be employed. Inbrief, the apparatus in question consists of a carbon block having atrough, or hollow, in its upper surface, which serve-s as the cruciblefor the production of the. alloy. This crucible is heated by internallydeveloped heat generated by the passage through its walls of anelectrical current, which is preferably an alternating current.

The metals to be alloyed, i. a, nickel and tungsten, each of whichshould be in a relatively pure state for the best results, areintroduced intonthe crucible and the latter raised to such a temperatureas to cause 85 them to fuse. Powdered amdrphous cari bon, or powderedgraphitic carbon is then introduced into the fused mass, the mass be- 7ing preferably stirred with acarbon stirring-rod. I also find it ofadvantage to 40 interrupt the current through the crucible at intervals.Within avery few minutes the molten mass within the crucible solidi-"fies or sets. The process is now at an end and the current may be turnedoff, the crucible permitted to cool and the block of metalcompositionremoved therefrom. This blocm'f may then be machined, ground orotherwise fabricated to produce contact points, or other structuralelements.

Specification of Letters Patent. Application filed. March 23, 1917.Serial No. 156,973.

Although I prefer to stir in finely divided amorphous carbon, or finelydivided graphitic carbon, during the heating of the metal within thecrucible, this is not essential to the success of the process, since Ifind that the crucible walls themselves are eaten away during theprocess, the carbon required for the composition being thus supplied toa large extent by the crucible itself.

I find that by the process above. described, I am able to produce ametal com- Patented June 4, 1918.

position which is substantially homogenous throughout its mass and whichupon analysis shows a percentage of carbon (by weight) of from 2% to 7per cent. Forthe manufacture of contact points I prefer to use for mymetal composition substantially pure nickel and tungsten in abouttheproportions of 4 parts of nickel to one part of tungsten. The metalcomposition having these constituents I find to be superior to thecomposition described in myprior application above referred to, in thatit is considerably harder and has a longer life when used as a contactpoint and subjected to the arcing and sparking which is there met with.

My new metal .composition herein described possesses the peculiaritiesand advantages of the composition described in my prior applicationabove referred to, and in addition is superior to the last-named composition in the respects pointed out.

What I claim as new, and desire to secure I by Letters Patent, is:

1. A metal composition comprising substantially an alloy of more than 50per cent. of nickel and less than 50 per cent. of tungsten carryingupward of 3 per cent. of uncombined carbon.

2. A contact point for making and breaking electrical circuits andcomprising substantially an alloy of more than 50 per cent.

of nickel and less than 50 per cent. of

.uncombined carbon:

' 3. A metal composltion comprising substantally an alloy of'four partsof nickel :tungsten carrying upward of- 3 per cent. of

4. A contact point for making and breaking electrical circuits andcomprising substantially an alloy of four parts of nickel and one partof tungsten carrying upward 5 of 3 per cent. of uncombined-carbom 5. Acast metal contact point for-making and breaking electrical circuits andcomprising upward of 7 0 per cent. of nickel, upward of 20 per cent. oftungsten, and upward of 3 per cent. of graphitic carbon. 10 6. A castmetal composition comprising substantially an alloy of-upward of 50 percent. of nickel and less than 50 per cent. of tungsten carrying upwardof 3 per cent. of graphitic carbon. J HENRY K; SANDELL.

